naive, acute, full-fledged, benign, autoimmune, chronic, kiddish, communicable, congenital, fully-grown, puerile, babyish, asymptomatic, fully-fledged, cherubic, catching, infantine, advanced, developed, full-grown, grown, growth, youth, full-blown, jejune, clinical, childlike
beginning (part of speech: adjective)
foremost, incipient, hatching, maiden, fetal, commencing, initial, early, dawned, preparatory, formative, first, beginning, nascent, primal, primeval, Genesis, introductory, aboriginal, germinal, alpha, newborn, new, original, precursory, inaugural, preliminary, embryonic, sprouting, primordial, budding, emerging, infant, starting, baby
juvenile (part of speech: adjective)
- This confusion is common in infantile speech, e. - "The Romance of Names", Ernest Weekley.
- She gave him a demure glance under her infantile lashes. - "Kildares of Storm", Eleanor Mercein Kelly.
- They were fitted for the new reading public for this reason; the constant repetition of the same characters, events, scenes, plots, gave their infantile minds the pleasure which children find in having a story told over and over in exactly the same terms. - "Imaginary Interviews", W. D. Howells.